This invention relates to a folding wheeled chair/luggage carrier having a pair of side frames, each comprising pivotally connected, elongated base and back support members, at least one elongated strut which is pivotally connected between the free ends of said support members, releasable locking means for maintaining a desired angular relationship between said base and back support members, and a strut bracing member interconnecting the locking means and said pivotal connection, and lateral bracing means connecting said side frames whereby the latter are movable between an extended, use position in which they maintain the side frames in spaced side-by-side relationship and a retracted, stowage position.
Many prior art folding wheel chairs have side frames of generally triangular form, i.e. with a single diagonal strut for each side frame, which strut is in the form of a pair of pivotally connected upper and lower strut members which can be maintained in an extended, aligned condition. The frame members are generally made from lightweight, strong material such as aluminum tubing and are particularly suitable for use as strollers for small children. As example, of such folding wheel chairs is described in U.S. Pat. No. 3,797,848.
Other folding wheel chairs are intended for adults, e.g. invalids or crippled persons, in which case the frame structure needs to be capable of withstanding not only the extra weight of the occupant, but also loads caused when the chair is traveling over uneven grounds, or is tilted to cope with a curb, stair or the like. Because the frame structure of such a chair needs to be of sturdier construction, the side frames are often of quadrilateral instead of triangular form. Also, because of the extra loads involved, the design must be such that it is most unlikely to collapse in use. Side frames of quadrilateral form tend to be more stable in use since the upright frame members are substantially vertical; hence, loads are taken mostly in compression. Because of resistance to loading required, such chairs are significantly heavier and more complicated than strollers for small children. An example of such a chair is described in U.S. Pat. No. 3,968,991.
U.S. Pat. No. 3,736,021 describes a relatively lightweight folding wheel chair which is based on the design for a stroller with triangular side frames. This chair design is said to be capable of supporting an occupant of up to 154 lbs. in weight. In this design, the chair seat is suspended at least partially from the side frame strut members. Consequently, said strut members can be subjected to significant bending stresses which would tend to be concentrated in the area of the pivot connections on said strut members.
An object of the present invention is to provide a folding wheeled chair/luggage carrier which overcomes shortcomings of the prior art by its particular design of triangular side frames, which, in use, significantly reduces the bending stresses occurring on the pivot connections in the strut members.
Another object of the present invention is to provide such a folding wheeled chair/luggage carrier with locking means for the pivot connections or the strut members of such a form that, in use of the chair, the weight of the occupant is used to ensure that said strut members cannot collapse.
A further object of the present invention is to provide such a folding wheeled chair/luggage carrier which is of a particularly simple, lightweight construction, which, however, is capable of supporting an adult of normal weight (e.g. a 13 to 15 lb. example of the invention can support a 200 lb. person).